NOTE: As their name suggests hints are not exactly Hitman Trilogy HD cheats, and are usually just simple (but very useful) tips on how you can unlock secret level, features, find hidden areas and such. Hopefully these will make playing Hitman Trilogy HD even more entertaining.

1st Kill (Bronze): A successful kill has been performed
1st Mission Complete (Bronze): You completed the first mission on any level
47 kills in a mission (Gold): A mission has been completed with precisely 47 kills
5 Expert Silent Assassins (Silver): 5 Silent Assassin ratings awarded on the Expert difficulty
5 Normal Silent Assassins (Silver): 5 Silent Assassin ratings awarded on the Normal difficulty
5 Professional Silent Assassins (Gold): 5 Silent Assassin ratings awarded on the Professional difficulty
All Assault Rifles collected (Bronze): All Assault Rifles collected and displayed in the training room
All Firearms collected (Gold): All Firearms collected and displayed in the training room
All Hand Guns collected (Bronze): All Hand Guns collected and displayed in the training room
All Heavy Weapons collected (Bronze): All Heavy Weapons collected and displayed in the training room
All Machine Guns collected (Bronze): All Machine Guns collected and displayed in the training room
All Melee Weapons found (Bronze): You have found all Melee Weapons
All Shotguns collected (Bronze): All Shotguns collected and displayed in the training room
All Sniper Rifles collected (Bronze): All Sniper Rifles collected and displayed in the training room
Expert Mode Complete (Silver): Completed expert difficulty
Firey Fire (Silver): You used explosives on a victim
Headshot (Silver): A successful headshot has been performed
Killed the wrong guy (Bronze): An innocent person has been killed
Normal Mode Complete (Bronze): Completed normal difficulty
Perfect Assassin (Platinum): Unlock all trophies
Poisonous (Silver): You poisoned a victim
Professional Mode Complete (Gold): Completed professional difficulty
Silent Assassin (Bronze): A Silent Assassin rating has been awarded
Sleep well (Silver): You knocked a victim out